Big-breasted mother Nishizawa Momoka lives in a single-parent household, struggling with her relationship with her beloved son. As he reaches adolescence, he remains unable to wean himself from her breasts, bringing them up in nearly every conversation. Days of having her large, voluptuous breasts groped by him continue endlessly. Then one day, her affair with the local liquor store owner is exposed—she's caught in the act by her own son. Shy son Masaru, while folding laundry, suddenly reaches around from behind and begins groping her breasts. His mother panics and tries to stop him, but she can't break free. His hands won't stop, and as she feels their warmth, she finds herself overwhelmed with conflicted emotions.